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Program Highlights

Fibrous Networks in Liver Fibrosis

Animal tissues are composed of cells attached to either the surface of a fibrous network called a basement membrane or embedded within a 3D extracellular or interstitial matrix. As the disease liver fibrosis progresses, the extracellular fibrous networks become denser and more aligned. These physical changes lead to different mechanical properties and structures to which cells are exquisitely sensitive. To better understand the pathological effects of these changes during fibrosis on cells, we have engineered material platforms that mimic the extracellular matrix in tissue health and disease. As an example, we have fabricated fibrous materials that have varied mechanical properties and fiber densities when mechanically loaded due to the chemical adhesion between fibers, similar to natural extracellular matrix (see Figure).

Effects of extracellular matrix viscoelasticity on cellular behavior

Linearly elastic elastomers coated with matrix proteins are widely used to assess the role of stiffness. Such experiments are often assumed to reproduce the effect of the mechanical environment experienced by cells in vivo. However, tissues and the extracellular matrix (ECM) are not linearly elastic materials. They exhibit far more complex mechanical behaviors. These behaviors include viscoelasticity, as well as mechanical plasticity, and nonlinear elasticity. Our theoretical and experimental work has revealed that matrix viscoelasticity regulates fundamental cell processes and can promote behaviors – such as proliferation, motility and spreading – that are not observed with elastic hydrogels in both two- and three-dimensional culture microenvironments.

The Perpetual Fragility of Creeping Hillslopes

Soil is a highly disordered granular material. Slow soil deformation (creep) controls the shape of hills in the natural landscape, and is a precursor of catastrophic landsliding. Our work demonstrates a surprising observation: an apparently static sandpile, sitting on a table, is actually alive with motion. We study a 3D granular heap, confined by walls and prepared by pouring. Via Diffusive Wave Spectroscopy (DWS), we observe the existence of spatially-heterogeneous micro-deformations that decay in size and frequency as time progresses but persist up to 11 days after the preparation of the system; the heap relaxes. We find that this relaxation can be enhanced  (overaged) or reversed (rejuvenated) by tuning the types of disturbances applied to system.

Surface Modification of Black Phosphorus with Group 13 Lewis Acids for Ambient Protection and Electronic Tuning

We have developed a solution-phase protocol to modify the Lewis basic surface of few-layer black phosphorus (bP) using commercially available Lewis acids, and demonstrated its effectiveness at providing outstanding ambient stability and tuning of electronic properties.

Tunable Correlated and Topological States in Twisted Graphene Multilayers

Stacking various atomically-thin crystals on top of one another can strongly modify their overall properties. When two materials are stacked with a twist angle, a geometric interference pattern (a moiré pattern) emerges. At special twist angles, the moiré pattern can result in new electronic states dominated by strong correlations between electrons.

Holiday Lecture 2020: A Materials Wonderland

PCCM celebrated its annual Holiday Lecture 2020: A Materials Wonderland: A Celebration of How Materials Science Make Our Holidays Fun with PCCM faculty, research members and others providing (virtual) materials science presentations. The audience helped with experiments and demonstrations from their homes. 426 families registered, some with multiple children (tuning from all over the world), resulting in ~1,000 attendees!

Discovery of Intrinsic Landau Quantization in an Insulator

In a surprising discovery, Princeton physicists have observed an unexpected quantum behavior in an insulator made from a material called tungsten ditelluride. This phenomenon, known as quantum oscillation, is typically observed in metals rather than insulators, and its discovery offers new insights into our understanding of the quantum world. The findings also hint at the existence of an entirely new type of quantum particle.

Multi-qubit Entanglement in a Quantum Network

The Cleland and Schuster groups at the University of Chicago have demonstrated multi-bit entanglement in a Quantum Network.

Sculpting and Predicting Flows in Active Nematics

The Gardel lab at the University of Chicago has realized an active liquid crystal where the active stresses could be modulated spatiotemporally through selective illumination with blue light.

Metallic “Defect Wires” in a Semiconducting Oxide

Semiconductors, which have electrical properties in between metals and insulators, are the building blocks of devices like transistors that fuel computer technology. New semiconducting materials that could outperform existing ones are continuously sought in science and engineering, with oxides being one contender.